[R] Fortran and long integers

[Earl F Glynn]

Peter Langfelder wrote:
> Hi all,
>
> I'm hoping someone more knowledgeable in Fortran than I can chime in
> with opinion.
>
> I'm the maintainer of the flashClust package that implements fast
> hierarchical clustering. The fortran code fails when the number of
> clustered objects is larger than about 46300. My guess is that this is
> because the code uses the following construct:

2-byte (16 bit) signed integers would have a range from -32768 to 
+37267.  So, it looks like you may be using 2-byte integers and 46,300 
would definitely cause an overflow with 16-bit integers.

I haven't used Fortran for a long time, but there could be a compiler 
switch that forces all 2-byte integers, or a specific declaration that 
says I, J, N, IOFFSET are only 2-byte (16-bit) integers.

I'm guess, but you might try a specification like

   INTEGER*4 I, J, N, IOFFSET

assuming INTEGER*4 is legal with your Fortran compiler:

http://gcc.gnu.org/onlinedocs/gfortran/Old_002dstyle-kind-specifications.html#Old_002dstyle-kind-specifications

efg

Earl F Glynn
Overland Park, KS